ASSESSMENT OF THE ACCURACY AND PRECISION OF A PATIENT IMMOBILIZATION DEVICE FOR RADIATION THERAPY IN CANINE HEAD AND NECK TUMORS

The positioning accuracy and precision of a head and neck immobilization device for radiation therapy of tumors in the canine skull was evaluated. Nineteen dogs with a spontaneous tumor of the head were enrolled including 12 with an intracranial mass and seven with an intranasal or maxillary tumor. Three hundred thirty-three pairs of orthogonal digital portal radiographs were analyzed to assess patient displacement in the cranial–caudal, lateral, and dorso-ventral directions. The mean systematic displacement was 0.8, 1, and 0.9 mm. The mean random displacement was 1.9, 1.6, and 1.5 mm. These values resulted in an overall displacement of 2.1 mm in the cranial–caudal direction, 1.8 mm in the lateral direction, and 1.7 mm in the dorsal–ventral direction. The mean displacement value of the three dimensional (3D) vector was 2.4 mm with a standard deviation of 2.1. Ninety-five percent of all vectors were <6.4 mm. This study quantifies the precision and accuracy of this particular positioning device. Knowing the limitations and setup variability of the system being used to set patients up for daily radiotherapy is paramount to planning and delivering appropriate radiation doses, especially as more complex treatment methods are used.     

Management of cases suffering from atypical myopathy: Interpretations of descriptive,epidemiological and pathophysiological findings. Part 1: First aid,cardiovascular, nutritional and digestive care

Atypical myopathy is highly fatal, but about a quarter of affected horses survive. This highlights the need for provision of supportive treatment for these cases. This review is a practical guideline for equine practitioners and includes suggestions for close monitoring of involved organ systems and discusses options of supportive treatment based on current knowledge of the condition.     

Tolerability of metronomic administration of lomustine in dogs with cancer

Background: Metronomic chemotherapy with alkylating agents has been shown to suppress tumor angiogenesis and prevent tumor recurrence in some settings. The use of adjuvant lomustine (1‐(2‐chloroethyl)‐3‐cyclohexyl‐1‐nitrosourea) administered in a metronomic fashion has not been evaluated in dogs. Hypothesis: Oral metronomic administration of lomustine will be well tolerated in dogs with spontaneously occurring malignant neoplasms. Animals: Eighty‐one dogs with naturally occurring primary or metastatic tumors received metronomic administration of lomustine. Methods: Dogs were enrolled prospectively after cytological or histological diagnosis of a tumor that was unresectable, incompletely resected, refractory to chemotherapy, or metastatic. Dogs received once daily lomustine (2.84 mg/m² PO). End points of the trial were clinical, hematologic, or biochemical evidence of toxicosis, tumor progression, or death. Results: Starting dosage (median) was 2.84 mg/m² PO daily and treatment duration was 98 days (median, range, 1–770 days). The drug was discontinued in 22 dogs because of toxicoses. Toxicoses occurred in 13 dogs with gastrointestinal toxicosis, 4 dogs with thrombocytopenia, 3 dogs with increased alanine transaminase, 1 dog with neutropenia, and 1 dog with progressive azotemia. Eight dogs developed some degree of azotemia during treatment. Hepatotoxicosis was observed at a median of 265 days in 11 dogs. Thrombocytopenia was identified at a median of 432 days of administration. Conclusions and Clinical Importance: In dogs with metastatic or terminal neoplasms without renal compromise, metronomic administration of lomustine was well tolerated. This can provide a treatment strategy for dogs that do not have other standard‐care treatment options, and warrants evaluation in primary therapy.     

Cardiovascular,Colloid Osmotic Pressure,and Hemostatic Effects of 2 Formulations of Hydroxyethyl Starch in Healthy Horses

Background

Lower molecular weight and molar substitution formulations of hydroxyethyl starch (HES) solutions might maximize cardiovascular function and colloid osmotic pressure (COP) and minimize adverse effects on coagulation.

Hypothesis/Objectives

To compare effects of 1 low and 1 high molecular weight and molar substitution HES solution on cardiovascular variables, COP, and hemostasis in normal horses.

Animals

Eight healthy adult horses.

Methods

Randomized, crossover designed study: 10 mL/kg bolus of 6% HES (600/0.75) (hetastarch) (HS), 6% HES (130/0.4) tetrastarch (TS), and 0.9% NaCl (NS). Variables recorded included central venous pressure (CVP), noninvasive arterial blood pressure, packed cell volume (PCV), COP, and automated platelet analysis (CT).

Results

Central venous pressure was increased for 8 hours after all treatment (baseline = 8.4 ± 3.8; 8 hours = 10.3 ± 3.5 cm H₂O; P < .001). HS and TS produced an increase in systolic arterial pressure (HS = 109.1 ± 11.9; TS = 109.5 ± 10.9 mmHg) and mean arterial pressure (HS = 80.4 ± 13.0; TS = 82.3 ± 10.1 mmHg) compared to NS (SAP = 103.2 ± 13.2 [P = .023]; MAP = 74.2 ± 11.4 mmHg [P = .048]). PCV decreased transiently with HS (baseline = 37.1 ± 4.4%; 1.5 hours = 31.6 ± 3.9%) and TS (baseline = 38.4 ± 3.9%; 1.5 hours = 32.2 ± 3.3%), but not NS (P = .007). COP was greater with HS (1 hour; 24.0 ± 2.1 mmHg) and TS (8 hours; 25.9 ± 2.1 mmHg) than NS (1 hour = 20.8 ± 2.6; 8 hours = 22.9 ± 3.1 mmHg; P < .001). CT was greater at 8 (HS = 178.6 ± 36.9; TS = 121.9 ± 33.3; NS = 108.3 ± 23.6 seconds) and 24 hours (HS = 174.2 ± 41.7; TS = 100.8 ± 26.0; NS = 118.7 ± 38.7 seconds; P < .001) in horses receiving HS than TS or NS.

Conclusion and Clinical Importance

Both TS and HS resulted in more effective volume expansion and arterial pressure support than NS. TS produced a more sustained effect on COP with shorter duration of adverse effects on platelet function than HS.     

Induced Acute Ruminai Acidosis in Goats Treated with Yeast (Saccharomyces cerevisiae) and Bicarbonate

Ruminai acidosis was induced in twenty-one 10-month-old West African Dwarf Goats by feeding a suspension of 80 g wheat flour per kg body-weight (day 0) through a stomach tube. Ruminai and systemic acidosis was diagnosed on day 1 in all goats. Clinical signs included loss of rumination and appetite, trembling, and watery diarrhoea. The detection of acidic faeces during the first 24h was considered of diagnostic importance. Subgroups were treated orally on days 1,2, and 3 either with 1 g of sodium bicarbonate per kg bodyweight, with 1 g of baking yeast per kg, or with a combination of these treatments at 0.5 g of each per kg. A fourth group served as untreated controls.Peroral bicarbonate neutralization was highly effective in the treatment of rumen acidosis, whereas the use of yeast was found ineffective. The combined treatment had a moderate effect probably due to the bicarbonate.Three fatal cases (60%) occurred in the untreated group compared with none in the bicarbonate group, and 2 in each of the remaining groups. This corresponded to 33% of the yeast treated group and 40% of the combined treated group. Details were given on post mortem examinations performed on all survivors on day 11. Lesions included subacute rumenitis and abomasal ulcers. No lesions were found in 3 of the bicarbonate treated goats and in 2 of the animals receiving combined treatment.     

Equine external beam radiation therapy: Techniques and challenges

Radiation therapy is becoming increasingly more available and in demand for small animal veterinary cases. Although there is a demand for radiation therapy in large animal cases, there are certain limitations of external beam radiation therapy for horses that restrict treatment options. Currently, there are only five veterinary teaching hospitals in the United States where external beam radiation therapy can be performed on horses and other large animals. This is in contrast to the roughly 80 facilities, both academic and private, available for small animals. The goal of this commentary is to give a brief overview of external beam radiation therapy and highlight the steps involved, and the technical difficulties faced, while treating horses with external beam radiation therapy.     

A new cell culture protocol for enrichment and genetic modification of adult canine Schwann cells suitable for peripheral nerve tissue engineering

Easily applicable techniques are presented to obtain high numbers of enriched canine Schwann cells (cSC) in a short time-window. The potential of adult SC for tissue engineering of peripheral nerves and ex vivo gene therapy is obvious from physiological events taking place after peripheral nerve transection [Haastert, K., Grothe, C., 2007. Gene therapy in peripheral nerve reconstruction approaches. Curr. Gene Ther. 7, 221-228]. The presented techniques were modified from a protocol for cultivation and expansion of adult cSC by others [Pauls, J., Nolte, C., Forterre, F., Brunnberg, L., 2004. Cultivation and expansion of canine Schwann cells using reexplantation. Berl. Munch. Tierarztl. Wochenschr. 117, 341-352] and own experiences in rodent and human SC cultivation and transfection [Haastert, K., Mauritz, C., Chaturvedi, S., Grothe, C., 2007. Human and rat adult Schwann cell cultures: fast and efficient enrichment and highly effective non-viral transfection protocol. Nat. Protoc. 2, 99-104]. A purity of about 80% cSC achieved by immunopanning techniques and selective culture conditions is 2.5 fold higher as previously reported (Pauls et al., 2004). Additionally, highly enriched cSC populations are available in 3-4 weeks, only half the time period reported previously (Pauls et al., 2004). Furthermore, electroporation and genetic modification of cSC is reported for the first time.     

USE OF PORTAL RADIOGRAPHY TO INCREASE ACCURACY OF DOSE DELIVERY IN RADIATION THERAPY

Port films were acquired for all radiation therapy patients (n = 132) treated over a thirteen month period to 1] assist in initial treatment field set-up on Day 1, 2] for quality assurance with a second port film taken on Day 7 of radiation therapy, and 3] as a means to document the radiation treatment field as a part of the patients permanent medical record. Port films were used for both patients treated with a definitive course of radiation (n = 97 patients), and those treated palliatively (n = 35 patients). The portal radiographs were valuable in terms of the initial set-up, and to correct for any positioning or other errors at the time of the one week recheck. Changes were made, based on the initial port film on Day 1, in 53% and 57% of treatment fields for palliative and definitive radiation patients, respectively. The changes made in both definitively and palliatively irradiated patients were usually in field position, an increase in field size to include all of the tumor, or a decrease in field size to spare normal tissue. Fewer changes were necessary based on the Day 7 recheck port films, but these day-7 rechecks are recommended for quality control. Based on the high frequency of changes introduced because of the initial port film findings, it is recommended that port films be incorporated on a routine basis in veterinary radiation therapy.     

Management of cases suffering from atypical myopathy: Interpretations of descriptive,epidemiological and pathophysiological findings. Part 2: Muscular,urinary, respiratory and hepatic care,and inflammatory/infectious status

Atypical myopathy is highly fatal, but about a quarter of affected horses survive. This highlights the need for provision of supportive treatment for these patients. This review is a practical guideline for equine practitioners and includes suggestions for close monitoring of involved organ systems and discusses options of supportive treatment based on current knowledge of the condition. Part 2 covers the muscular, urinary, respiratory and hepatic systems, and the general inflammatory/infectious status of the case.     

A complication probability study for a definitive‐intent,moderately hypofractionated image‐guided intensity‐modulated radiotherapy protocol for anal sac adenocarcinoma in dogs

Previous trials showed the importance of administering radiation therapy (RT) with small doses per fraction in canine pelvic tumours to maintain acceptable toxicity levels. With increased accuracy/precision of RT, namely intensity‐modulated RT (IMRT), this approach might be challenged. Theoretical toxicity calculations for a new definitive‐intent moderately hypofractionated RT protocol for canine anal sac adenocarcinomas (ASAC) were performed, focussing on the risk of toxicity in pelvic organs at risk (OAR). Computed tomography datasets of 18 dogs with stage 3b ASAC were included. Re‐planning with margins for daily image‐guidance/IMRT was performed and a new protocol isoeffective to previously described definitive‐intent protocols was computed. Dose‐volume information were derived from individual plans and used for normal tissue complication probability (NTCP) computations. A 12 × 3.8 Gy protocol was computed for risk estimation. Tumour volumes ranged from 27.9 to 820.4 cm³ (mean 221.3 cm³ ± 188.9). For late rectal toxicity/bleeding ≥grade 2, median risk probability was 2.3% inter quartile range (IQR: 5.9; 95% confidence interval (CI): 1.2, 8.4) (rho = 0.436) and 3.4% (IQR: 0.96; 95%CI: 3.1, 4.0) (rho = 0.565), respectively. Median late toxicities in urinary bladder, kidneys and small bowel were <1%, except in one kidney. Myelopathy/myelonecrosis had a median risk probability of 4.1% (IQR: 23.5; 95%CI: 2.1, 25.2) (rho = 0.366) and 5.6% (IQR: 13.5; 95%CI: 3.1, 14.1) (rho = 0.363), respectively. However, graded risk showed a probability estimate for late spinal cord toxicity of ≥5% in 8/18 patients. The daily‐imaging IMRT 12 × 3.8 Gy protocol for canine ASAC seems tolerable for most cases, even in advanced disease. Theoretical dose computations serve as estimate, but are safe measures before implementing new protocols into clinical use.